Musar for Pirkei Avot 3:2
רַבִּי חֲנִינָא סְגַן הַכֹּהֲנִים אוֹמֵר, הֱוֵי מִתְפַּלֵּל בִּשְׁלוֹמָהּ שֶׁל מַלְכוּת, שֶׁאִלְמָלֵא מוֹרָאָהּ, אִישׁ אֶת רֵעֵהוּ חַיִּים בְּלָעוֹ. רַבִּי חֲנִינָא בֶן תְּרַדְיוֹן אוֹמֵר, שְׁנַיִם שֶׁיּוֹשְׁבִין וְאֵין בֵּינֵיהֶן דִּבְרֵי תוֹרָה, הֲרֵי זֶה מוֹשַׁב לֵצִים, שֶׁנֶּאֱמַר (תהלים א) וּבְמוֹשַׁב לֵצִים לֹא יָשָׁב. אֲבָל שְׁנַיִם שֶׁיּוֹשְׁבִין וְיֵשׁ בֵּינֵיהֶם דִּבְרֵי תוֹרָה, שְׁכִינָה שְׁרוּיָה בֵינֵיהֶם, שֶׁנֶּאֱמַר (מלאכי ג) אָז נִדְבְּרוּ יִרְאֵי יְיָ אִישׁ אֶל רֵעֵהוּ וַיַּקְשֵׁב יְיָ וַיִּשְׁמָע וַיִּכָּתֵב סֵפֶר זִכָּרוֹן לְפָנָיו לְיִרְאֵי יְיָ וּלְחֹשְׁבֵי שְׁמוֹ. אֵין לִי אֶלָּא שְׁנַיִם, מִנַּיִן שֶׁאֲפִלּוּ אֶחָד שֶׁיּוֹשֵׁב וְעוֹסֵק בַּתּוֹרָה, שֶׁהַקָּדוֹשׁ בָּרוּךְ הוּא קוֹבֵעַ לוֹ שָׂכָר, שֶׁנֶּאֱמַר (איכה ג) יֵשֵׁב בָּדָד וְיִדֹּם כִּי נָטַל עָלָיו:
R. Chanina, the adjutant high-priest says: Pray for the well-being of the king, [even the kings of the nations]. For if not for its [(monarchy's)] fear, one man would swallow his fellow alive, [as it is written (Habakkuk 1:14): "And You have made a man like the fish of the sea" — Just as with the fish of the sea, all who are bigger than the other swallow the other, so with men. If the fear of the king were not upon them, all who were greater than the other would swallow the other.] R. Chanina ben Teradyon says: If two sit and there are no words of Torah between them, this is called "the seat of scoffers," as it is written (Psalms 1:1): "And he did not sit in the seat of scoffers. ((2): For in the Torah of the L rd is his desire, etc.") But if two sit and there are words of Torah between them, the Shechinah is between them, as it is written (Malachi 3:16): "Then the fearers of the L rd spoke to each other [(two are implied)], and the L rd listened and heard, and a book of remembrance was written before Him for the fearers of the L rd and the thinkers on His name." This tells me only of two. Whence do I derive that even if one sits and studies Torah the Holy One Blessed be He sets aside reward for him? From (Eichah 3:27): "He shall sit alone and be silent, [learning by himself in "a still, small voice"], for he has taken it upon him" [i.e., it is as if the giving of the entire Torah was for him alone.]